The invention relates to an electrolyser for highly-active tritiated water, which electrolyser comprises a cell which has a tightly-sealed cell housing, an inorganic porous gas separator which divides the cell housing into two compartments, two electrodes which are respectively mounted in the two compartments, current-supply lines which connect to the electrodes, two gas outlets which connect respectively to the two compartments and at least one liquid inlet which opens on the cell housing inner side.
Such electrolysers are used to recover from the tritiated water which is formed inside a deuterium-tritium fusion reactor, in various locations and mostly when extracting tritium from the breeding material and when purifying the plasma discharge gases, tritium in the form of DT gas which can be used anew in the fuel cycle.
The breaking-down of tritiated water by electrolytic dissociation is considered as one of the best methods for recovering the tritium, as it allows limiting the amount solid tritiated waste and avoiding tritium permeation at high temperature.
An electrolyser making use of existing SPE (Solid Polymer Electrolyte) cells developed by General Electric Company is not suitable for the electrolysis of highly-active tritiated water. The life duration would be but ten hours where an electrolyser for tritium has preferably a life duration of 10.sup.4 hours.
The gas separator made from organic material does not apparently withstand the high radiation.
Moreover with electrolysis by means of such an electrolyser, a high proportion tritiated water is present in the gas lines.
The electrolyser life duration is markedly improved by making use of an inorganic porous gas separator as in the electrolyser of the above-defined type.
In a first known electrolyser of this kind, the inorganic porous gas separator is made from asbestos. Said flat gas separator is arranged vertically and moistened with 6 M-NaOH, and 1 M-NaOH is continuously sprayed on said separator.
Said electrolyser has however a large liquid content and particularly a large electrolyte content. The necessity of spraying the gas separator with 1 M-NaOH requires electrolyte flow by means of a pump which is mounted outside the electrolysis cell proper. Such flow is a drawback. Moreover due to spraying the gas separator with electrolyte, there is formed an undesirable electrolyte mist in the oxygen gas stream, in such a way that "demisters" are required to remove such mist. The system for spraying electrolyte on the gas separator also has a limited durability.
A second known electrolyser with an inorganic porous gas separator has a ceramic gas separator from stabilized zirconium with 8% CaO.
In this electrolyser, no liquid electrolyte is being used. Said electrolyser works then also at very high temperatures, which has a disadvantageous influence as regards corrosion and tritium permeability, and causes metal embrittlement. A very high tritiated water content is also present in the tritium gas. Said known electrolyser has a low tritium-recovery capacity.